Explain how vaccines lead to immunity against a pathogen

II. Procedure1. You will need to partner with someone in your house to do this experiment. (A third personis helpful as a timer if available but not essential). Face that person and hold each other’shands so that you are both capable of squeezing each other’s hand. The first person isinstructed to squeeze the left hand of the other person with their right hand. As soon as theother person feels the squeeze, they can squeeze the first person’s left hand with their righthand. Then you will continue the cycle. As soon as the first person feels the squeeze ontheir left hand, they squeeze the second person’s left hand and on and on. In this way youhave now made a loop of conduction (basically a human circuit).2. What is the neural signaling process involved in this? Tactile detectors in the left handdetect a squeeze, a neural impulse travels from their hand up their arm and to their dorsalroot ganglia (clusters of neurons) next to the spinal cord where it connects to (synapseswith) another set of neurons that send signals up the spinal cord to the brain, where variousthings happen (including activating the memory instruction to now squeeze with the righthand), neural signals commence to orchestrate the appropriate muscle movement andseveral synapses later the right hand squeezes the hand of the other person. Draw a sketchof this process in the space below.3. After several rounds of practice, we now measure the total time for the squeeze-squeezeeffect to propagate for 10 full cycles (20 people worth because each cycle goes through twopeople), from you to the other person and back again. Once you have this time, divide by20 to get the time that it takes the signal to travel through one person (since there are twopeople, in 10 cycles the signal passes through a body twenty times). This will be how longit takes for each individual to detect the incoming sensory signal, execute the neededanalyses and decisions, and produce an outgoing muscle response.Time for the squeeze-squeeze effect: ______________ seconds4. Now, rather than hold hands, each person places their right hand on the left shoulder of theother. The instruction is the same, but instead of squeezing, tap the next person’s shoulder.Again, the first person will begin the process by tapping the left shoulder of the secondperson with their right hand; that person, as quickly as possible, taps the shoulder of thefirst person; and so on. After several rounds of practice, we now measure the total time orthe tap-tap effect for ten full cycles. Again divide by 20 to get the average time for thesignal to propagate through each body.Time for the tap-tap effect: ______________ secondsQuestion: If things go right, the total time for the tap-tap effect will be less than the totaltime for the squeeze-squeeze effect. What is that difference?Squeeze-Squeeze Time - Tap-Tap Time = ΔT = ______________ seconds5. In the squeeze-squeeze case, there is an additional arm's length (from left hand to leftshoulder) that must be transmitted by a neural signal as compared to the tap-tap case. Usingthe simple speed equation (without acceleration), determine the easy equation you woulduse to find the nerve conduction speed in a human arm using the difference in time betweensqueeze-squeeze and tap-tap that you determined above. Write the equation below.6. If you did step 5 correctly, then you should know that in order to calculate the conductionspeed you will need to know the average arm lengths of you and your partner, shoulder tothe tips of the finger. Find these lengths using a ruler and input the info below for eachperson. Then add them and divide them by two to find the average.7. Using your equation from step 5, calculate the conduction speed of the human body below:ANALYSIS 1. Free nerve endings associated with touch and pressure are known to have conductionspeeds between 3-30m/s. Do your results fall into this range?2. Take the mid-value of the above range. What is the percent difference between this valueand the results you got in the experiment?3. Describe in thorough detail at least one source of error that could have disturbed theaccuracy of your results. Describe specifically how it would have affected your results.Would it have made the magnitude greater? Less? Why?4. Using what you learned in lecture, estimate the resistance of your full arm, finger toshoulder. Note: there is no right answer here. The values will differ. You just want to getthe right order of magnitude.5. The voltages associated with nerve conduction are usually on the order of 70 mV. Usingthis fact and the answer to question 4, give a rough estimate for the current travelingthrough your arm during standard nerve conduction.6. Describe in thorough and clear detail how electric signals are propagated through nervecells. In other words, describe an action potential and how such a signal is then transferredonto the next neuron and so on. Use pictures and words if necessary.